This invention relates to an over-the-road trailer hitch for use on intermodal railcars, and, more particularly, to such a hitch for use on a "spine type" intermodal railway car which is utilized to transport both over-the-road trailers and large shipping containers.
Trailer hitches for use on intermodal railway cars are well known in the art. Typically, these trailer hitches are used on so-called "piggy back" intermodal railcars to secure over-the-road trailers on the railcar. In recent years, railroads have developed large terminals for handling intermodal shipments in which the trailers are lifted on and off the car either by means of a bridge crane straddling the track, or by means of large fork lifts or the like. In certain applications, to give shippers additional flexibility, such intermodal cars are designed to handle large containers as well as over-the-road trailers. So that the railcar may have this dual use capability, it is necessary that the trailer hitch be retractable so that it will not interfere with the container when the railcar is used to transport containers. Typically, these retractable hitches are moved from their lowered or retracted position to their erected or raised position either manually through use of a manually operated screw jack mechanism or the like, or are erected using the crane to lift the retracted hitch.
Typically, a retractable hitch includes a first or generally vertical strut and a second or diagonal strut. The upper ends of these struts are pivotally connected to a hitch head which serves as a fifth wheel for supporting the front end of the trailer and for positively holding the trailer on the railcar. The hitch head includes releasable jaws or the like for positively engaging the king pin of the trailer. The hitch is typically the only means holding the trailer in place on the railcar when it is underway. At its destination, the hitch head is actuated so as to release the trailer kingpin thereby to permit the trailer to be offloaded.
In addition to the manually operable or crane operable retractable hitch described above, another known hitch is referred to as a tractor operated hitch. As an alternative to utilizing a crane or other lifting equipment to load and off-load trailers from an intermodal railway car, it is well known to use a "circus" loading/off-loading technique in which a trailer coupled to a tractor is driven lengthwise onto the railcars and from one car to another until reaching a desired position. The tractor engages a retracted hitch on the car, raises the hitch, and transfers the trailer from the tractor to the raised hitch. Likewise, in off-loading a trailer, the tractor actuates a retraction mechanism for the hitch and transfers the trailer from the hitch to the tractor while permitting the hitch to move to its retracted position. Examples of prior art crane operated and tractor operated hitches, and of hitch heads are shown in the following U.S. Pat. Nos. 4,185,564, 4,193,350, 4,216,726, 4,221,397, 4,225,276, 4,230,430, 4,230,431, 4,239,429, 4,264,250, 4,397,594, 4,407,617, and 4,563,117.
In recent years, an intermodal railcar has been developed which is referred to as a "spine-type" car which has a center through sill beam extending the length of the car with intermittent platforms provided at the sides of the car for supporting the wheels of an over-the-road trailer. A hitch is provided on the spine structure of the car for supporting the forward end of the trailer. Typically, each intermodal spine-type car carries five (5) over-the-road trailers. These spine-type cars may also be utilized to carry containers, for which use the hitch must be retracted.
In accordance with this invention, a manually operable release mechanism is provided for a retractable hitch which may be operated by a train attendant standing alongside of the car. When the release mechanism is actuated, the hitch is free to move toward its retracted position under the bias of gravity. Because such hitches are heavy (e.g., 1500 lbs. or more), the hitch will rapidly move to its retracted position with great force. Thus, these hitches, as they are falling toward their retracted position, can cause physical injury to a train attendant not clear of the hitch and the hitch can cause damage to the railcar or to the hitch due to the impact during falling movement.